This invention relates to a dock leveler used to bridge the gap between a loading dock and the bed of a truck or carrier parked adjacent the loading dock, and more particularly to improvements in dock levelers incorporating an airbag or other inflatable member for raising the ramp of the dock leveler.
A dock leveler typically includes a frame or supporting structure mounted in a pit or depression in the loading dock. The rear end of a ramp or deck plate is pivotally mounted to the supporting structure so that the ramp is movable between an inclined position in which the ramp is supported by the truck bed, a horizontal inoperative position, and a raised position in which the forward end of the ramp is raised above the truck bed.
An extension lip is pivotally mounted to the forward end of the ramp, and is movable between a downwardly hanging pendant position and an extended position in which the lip forms an extension to the ramp.
After a truck has parked in front of the loading dock in preparation for a loading or unloading operation, the ramp of the dock leveler is raised to its upwardly inclined position. As the ramp is lowered, the lip is pivoted outwardly to its extended position. As the ramp is subsequently lowered, the lip engages the bed of the truck to support the ramp, such that the ramp and the lip in combination bridge the gap between the loading dock and the truck bed. After the loading or unloading operation is completed, the ramp is raised and the lip falls by gravity to its pendant position. The ramp is then lowered to its horizontal position, and the truck can then pull away from the loading dock.
In the past, the ramp has been pivoted to its upward position in response to operation of a mechanical or hydraulic mechanism. However, recent developments in the dock leveler art disclose an inflatable member or bag utilized to pivot the ramp to its upwardly inclined position. These applications disclose a bag inflated with low pressure air by an inflating device such as a fan or blower, and are hereby incorporated by reference in their entirety.
It has been found that certain problems can occur when incorporating an inflatable member into a dock leveler. For example, if the inflatable bag directly interconnects the floor of the pit with the pivoting ramp, the bag can sometimes tear away from its interconnection with the ramp. Further the long distance between the pit floor and the ramp can cause lateral instability of the bag assembly.